Author
A. F. J. Levi
Other affiliations: Alcatel-Lucent, California Institute of Technology, AT&T ...read more
Bio: A. F. J. Levi is an academic researcher from University of Southern California. The author has contributed to research in topics: Laser & Semiconductor laser theory. The author has an hindex of 48, co-authored 275 publications receiving 9216 citations. Previous affiliations of A. F. J. Levi include Alcatel-Lucent & California Institute of Technology.
Papers published on a yearly basis
Papers
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TL;DR: In this paper, a new microlaser design based on the highreflectivity whisperinggallery modes around the edge of a thin semiconductor microdisk is described and initial experimental results are presented.
Abstract: A new microlaser design based on the high‐reflectivity whispering‐gallery modes around the edge of a thin semiconductor microdisk is described and initial experimental results are presented. Optical confinement within the thin disk plane results in a microresonator with potential for single‐mode, ultralow threshold lasers. Initial experiments use selective etching techniques in the InP/InGaAsP system to achieve 3–10 μm diameter disks as thin as 500 A suspended in air or SiO2 on an InP pedestal. Optically pumped InGaAs quantum wells provide sufficient gain when cooled with liquid nitrogen to obtain single‐mode lasing at 1.3 and 1.5 μm wavelengths with threshold pump powers below 100 μW.
1,383 citations
TL;DR: The I-V characteristics measured at 100, 300, and 400 K indicate that temperature strongly influences the ideality factor of graphene-silicon Schottky diodes, and the optical transparency of the thin graphene layer allows the underlying silicon substrate to absorb incident laser light and generate a photocurrent.
Abstract: We have fabricated graphene-silicon Schottky diodes by depositing mechanically exfoliated graphene on top of silicon substrates. The resulting current–voltage characteristics exhibit rectifying diode behavior with a barrier energy of 0.41 eV on n-type silicon and 0.45 eV on p-type silicon at the room temperature. The I–V characteristics measured at 100, 300, and 400 K indicate that temperature strongly influences the ideality factor of graphene–silicon Schottky diodes. The ideality factor, however, does not depend strongly on the number of graphene layers. The optical transparency of the thin graphene layer allows the underlying silicon substrate to absorb incident laser light and generate a photocurrent. Spatially resolved photocurrent measurements reveal the importance of inhomogeneity and series resistance in the devices.
457 citations
Journal Article•
TL;DR: In this article, the authors have fabricated graphene-silicon Schottky diodes by depositing mechanically exfoliated graphene on top of silicon substrates, and the resulting current-voltage characteristics exhibit rectifying diode behavior with a barrier energy of 0.41 eV on n-type silicon and 0.45eV on p-type Silicon at the room temperature.
Abstract: We have fabricated graphene-silicon Schottky diodes by depositing mechanically exfoliated graphene on top of silicon substrates. The resulting current–voltage characteristics exhibit rectifying diode behavior with a barrier energy of 0.41 eV on n-type silicon and 0.45 eV on p-type silicon at the room temperature. The I–V characteristics measured at 100, 300, and 400 K indicate that temperature strongly influences the ideality factor of graphene–silicon Schottky diodes. The ideality factor, however, does not depend strongly on the number of graphene layers. The optical transparency of the thin graphene layer allows the underlying silicon substrate to absorb incident laser light and generate a photocurrent. Spatially resolved photocurrent measurements reveal the importance of inhomogeneity and series resistance in the devices.
423 citations
TL;DR: It is shown that far-infrared radiation can be generated in the depletion field near semiconductor surfaces via the inverse Franz-Keldysh effect or electric-field-induced optical rectification.
Abstract: We show that far-infrared radiation can be generated in the depletion field near semiconductor surfaces via the inverse Franz-Keldysh effect or electric-field-induced optical rectification. This mechanism is conceptually different from those previously proposed and accounts for many recent experimental observations
274 citations
TL;DR: In this article, the threshold characteristics of InGaAs/InGaAsP microdisk lasers with optical emission near a wavelength λ = 1.52 μm were described and it was shown that more than 5% of the total spontaneous emission feeds into the lasing mode as the microdisk diameters reach 2 μm.
Abstract: This letter describes the threshold characteristics of InGaAs/InGaAsP microdisk lasers with optical emission near a wavelength λ=1.52 μm. More than 5% of the total spontaneous emission feeds into the lasing mode as the microdisk diameters reach 2 μm.
245 citations
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TL;DR: An overview and evaluation of state-of-the-art photodetectors based on graphene, other two-dimensional materials, and hybrid systems based on the combination of differentTwo-dimensional crystals or of two- dimensional crystals and other (nano)materials, such as plasmonic nanoparticles, semiconductors, quantum dots, or their integration with (silicon) waveguides are provided.
Abstract: Graphene and other two-dimensional materials, such as transition metal dichalcogenides, have rapidly established themselves as intriguing building blocks for optoelectronic applications, with a strong focus on various photodetection platforms The versatility of these material systems enables their application in areas including ultrafast and ultrasensitive detection of light in the ultraviolet, visible, infrared and terahertz frequency ranges These detectors can be integrated with other photonic components based on the same material, as well as with silicon photonic and electronic technologies Here, we provide an overview and evaluation of state-of-the-art photodetectors based on graphene, other two-dimensional materials, and hybrid systems based on the combination of different two-dimensional crystals or of two-dimensional crystals and other (nano)materials, such as plasmonic nanoparticles, semiconductors, quantum dots, or their integration with (silicon) waveguides
3,025 citations
Proceedings Article•
01 Jan 2005TL;DR: In quantum optical devices, microcavities can coax atoms or quantum dots to emit spontaneous photons in a desired direction or can provide an environment where dissipative mechanisms such as spontaneous emission are overcome so that quantum entanglement of radiation and matter is possible.
Abstract: Microcavity physics and design will be reviewed. Following an overview of applications in quantum optics, communications and biosensing, recent advances in ultra-high-Q research will be presented.
2,857 citations
Proceedings Article•
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TL;DR: In this paper, the authors describe photonic crystals as the analogy between electron waves in crystals and the light waves in artificial periodic dielectric structures, and the interest in periodic structures has been stimulated by the fast development of semiconductor technology that now allows the fabrication of artificial structures, whose period is comparable with the wavelength of light in the visible and infrared ranges.
Abstract: The term photonic crystals appears because of the analogy between electron waves in crystals and the light waves in artificial periodic dielectric structures. During the recent years the investigation of one-, two-and three-dimensional periodic structures has attracted a widespread attention of the world optics community because of great potentiality of such structures in advanced applied optical fields. The interest in periodic structures has been stimulated by the fast development of semiconductor technology that now allows the fabrication of artificial structures, whose period is comparable with the wavelength of light in the visible and infrared ranges.
2,722 citations
TL;DR: A laser cavity formed from a single defect in a two-dimensional photonic crystal is demonstrated and pulsed lasing action has been observed at a wavelength of 1.5 micrometers from optically pumped devices with a substrate temperature of 143 kelvin.
Abstract: A laser cavity formed from a single defect in a two-dimensional photonic crystal is demonstrated. The optical microcavity consists of a half wavelength–thick waveguide for vertical confinement and a two-dimensional photonic crystal mirror for lateral localization. A defect in the photonic crystal is introduced to trap photons inside a volume of 2.5 cubic half-wavelengths, approximately 0.03 cubic micrometers. The laser is fabricated in the indium gallium arsenic phosphide material system, and optical gain is provided by strained quantum wells designed for a peak emission wavelength of 1.55 micrometers at room temperature. Pulsed lasing action has been observed at a wavelength of 1.5 micrometers from optically pumped devices with a substrate temperature of 143 kelvin.
2,310 citations
06 Jun 2003
TL;DR: This work demonstrates a process for producing silica toroid-shaped microresonators-on-a-chip with Q factors in excess of 100 million using a combination of lithography, dry etching and a selective reflow process, representing an improvement of nearly four orders of magnitude over previous chip-based resonators.
Abstract: We demonstrate microfabrication of ultra-high-Q microcavities on a chip, exhibiting a novel toroid-shaped geometry. The cavities possess Q-factors in excess of 100 million which constitutes an improvement close to 4 orders-of-magnitude in Q compared to previous work [B. Gayral, et al., 1999].
2,177 citations